AoC (Advice of Charge) is a service which provides the means by which a user equipment may indicate the charge that will be made for the use of telecommunication services. In other words, AoC is a user-friendly service which informs an end-user about the cost of a transaction. In All-IP (All-Internet Protocol) networks this kind of service is even more important since there can be several application servers with different charges in the same transaction.
However, due to the fragmented network architecture, AoC cannot be implemented in All-IP networks in the same way as in GSM (Global System for Mobile communications).